Paul was adamant that the Church of Christ be one. Paul opened his letter to Church in Corinth with an appeal –“I appeal to you, brethren, by the name of our Lord Jesus Christ, that all of you agree and that there be no dissensions among you, that you be united in the same mind and the same judgment” (1 Corinthians 1:10). In a similar manner he implored the Church in Ephesus, “Christ Jesus himself being the cornerstone, in whom the whole structure is joined together” (Ephesians 2:20-21).
Paul preached a Church of sinners made holy through Christ Jesus “in whom the whole structure is joined together and into a holy temple in the Lord, in whom you also are build into it for a dwelling place of God in the Spirit” (Ephesians 2:21-22).
Paul’s epistles describe the universality (that is, catholic nature) of the Church of Christ, “There is neither Jew nor Greek, there is neither slave nor free, there is neither male nor female; for you are all one in Christ Jesus” (Galatians 3:28). Furthermore, to church in Ephesus he wrote, “So then, you are no longer strangers and sojourners, but you are fellow citizens with the saints and members of the household of God” (Ephesians 2:19).
Paul preached an apostolic church in his letters to Timothy and the churches in Ephesus and Thessalonica. In his letter to Timothy, Paul writes: “If I am delayed, you may know how one ought to behave in the household of God, which is the Church of the living God, the pillar and bulwark of truth” (Timothy 3:15). And, to the church in Ephesus he preached, “build upon the foundation of the apostles and prophets, Christ Jesus himself being the cornerstone” (Ephesians 2:20). In his epistle to the church in Thessalonica Paul taught “So then, brethren, stand firm and hold to the traditions, which you were taught by us, either by word of mouth or by letter” (2 Thessalonians 2:15).